1. Field of the Invention
The present invention relates to a content reproduction apparatus which reproduces and executes content data including video/audio information and a program recorded on a recording medium such as an optical disk, and more particularly, it relates to a content reproduction apparatus which accesses a server via a network.
2. Description of the Related Art
In recent years, there have been developed optical disk reproduction apparatuses to reproduce optical disks such as DVDs and video CDs in which data such as video and audio are recorded. These apparatuses are utilized in viewing movie software and the like, and they generally prevail.
The DVD is a specification concerning a disk which reproduces video/audio information recorded in an information recording medium, and has been issued as “DVD Specifications for Read-Only disk Part 3: VIDEO SPECIFICATIONS” by DVD Forum in 1996. In this specification, an MPEG 2 system is supported as a moving image compression system, and an MPEG audio compression system and an AC-3 audio compression system are supported as audio compression systems. Furthermore, there are defined: sub-video data which is bitmap data for use in a movie subtitle or the like; and control data (navigation pack) of quick forward reproduction, quick return reproduction or the like.
On the other hand, in recent years, with the prevalence of the Internet, there has been developed a video information device having a network access function. For example, in the video information device having a function of receiving and recording television broadcasting, there is developed a function of receiving data of an electronic program table from a server accessed via a network, and recording the broadcasting based on contents of the data.
As a conventional technology concerning the video information device having the network access function, there is disclosed an image display device which provides a service constituted of a DVD video title and an HTML file provided via the Internet in Document 1 (Jpn. Pat. Appln. KOKAI Publication No. 11-161663). In this image display device, it is possible to access the Internet based on URL taken out of the navigation pack and display an HTML content in conjunction with a scene being reproduced.
Moreover, in Document 2 (Jpn. Pat. Appln. KOKAI Publication No. 2004-79055), there is disclosed an optical disk device which not only displays the HTML content but also reproduces video having a high representation capability in accordance with extension information acquired from the server accessed via a communication circuit and which sends data in an optical disk to the server to perform certification processing so that the unspecified number of people cannot access the server.
However, in Document 1, there is not investigated a security problem caused when the content is acquired via the network. In Document 2, the certification processing is simply performed in order to limit the optical disk devices which can access the server, and there is no consideration of: a problem concerning a danger of acquiring a dangerous content maliciously prepared by the server of a destination; or a problem concerning a danger that the optical disk device becomes a steppingstone for an attack of distributed denial of service (DDoS), when the maliciously prepared dangerous content is reproduced. In the document, the security is insufficiently investigated.
As described above, in the conventional video information device having the network access function, the disk is certified to simply assure validity of the disk in order to limit the video information device which can access the server. Therefore, there is no consideration of: the problem concerning the danger of acquiring the dangerous content maliciously prepared by the server of the destination; or the problem concerning the danger that the video information device becomes the steppingstone for the DDoS attack or the like, when the maliciously prepared dangerous content is reproduced, and there is a problem that it is not possible to access the network with security.
Therefore, in view of the above-described problems, an object of the present invention is to provide a content reproduction apparatus and method capable of avoiding execution or reproduction of a disk on which tampered content data is recorded, and limiting a server to be accessed during the reproduction or the execution of the content data or program recorded on the disk.